package com.lagou.rpc.provider.handler;

import com.alibaba.fastjson.JSON;
import com.lagou.rpc.common.RpcRequest;
import com.lagou.rpc.common.RpcResponse;
import com.lagou.rpc.provider.anno.RpcService;
import com.lagou.rpc.provider.server.RpcServer;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import org.springframework.beans.BeansException;
import org.springframework.cglib.reflect.FastClass;
import org.springframework.cglib.reflect.FastMethod;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;

import java.lang.reflect.InvocationTargetException;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

/**
 * 服务端业务处理类
 * 1.将标有@RpcService注解的bean进行缓存
 * 2.接收客户端请求
 * 3.根据传递过来的beanName从缓存中查找对应的bean
 * 4.解析请求中的方法名称、参数类型、参数信息
 * 5.通过反射调用bean的方法
 * 6.给客户端响应
 */
@Component
@ChannelHandler.Sharable
public class RpcServerHandler extends SimpleChannelInboundHandler<RpcRequest> implements ApplicationContextAware {

    private static final Map SERVICE_INSTANCE_MAP = new ConcurrentHashMap();

    //1.将标有@RpcService注解的bean进行缓存
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        Map<String, Object> beansWithAnnotation = applicationContext.getBeansWithAnnotation(RpcService.class);
        if (beansWithAnnotation != null && beansWithAnnotation.size() > 0) {
            Set<Map.Entry<String, Object>> entries = beansWithAnnotation.entrySet();
            for (Map.Entry<String, Object> entry : entries) {
                Object serviceBean = entry.getValue();
                if (serviceBean.getClass().getInterfaces().length == 0) {
                    throw new RuntimeException("服务必须实现接口");
                }
                //默认取第一个接口作为缓存bean的名称
                SERVICE_INSTANCE_MAP.put(serviceBean.getClass().getInterfaces()[0].getName(), serviceBean);
            }
        }
    }

    /**
     * 通道读取就绪事件
     *
     * @param channelHandlerContext
     * @param rpcRequest
     * @throws Exception
     */
    @Override
    protected void channelRead0(ChannelHandlerContext channelHandlerContext, RpcRequest rpcRequest) throws Exception {
        //接收客户端请求 -  将msg转化为RpcRequest对象
//        RpcRequest rpcRequest = JSON.parseObject(msg, RpcRequest.class);
        RpcResponse rpcResponse = new RpcResponse();
        rpcResponse.setRequestId(rpcRequest.getRequestId());
        try {
            //业务处理
            rpcResponse.setResult(handler(rpcRequest));
        } catch (Exception e) {
            e.printStackTrace();
            if (StringUtils.isEmpty(e.getMessage())) {
                rpcResponse.setError(e.getCause().getMessage());
            } else {
                rpcResponse.setError(e.getMessage());
            }
        }
        //6.给客户端响应
//        channelHandlerContext.writeAndFlush(JSON.toJSONString(rpcResponse));
        channelHandlerContext.writeAndFlush(rpcResponse);
    }

    /**
     * 业务处理逻辑
     *
     * @return
     */
    public Object handler(RpcRequest rpcRequest) throws InvocationTargetException {
        // 3.根据传递过来的beanName从缓存中查找对应的bean
        String className = rpcRequest.getClassName();
        Object serviceBean = SERVICE_INSTANCE_MAP.get(className);
        if (serviceBean == null) {
            throw new RuntimeException("根据beanName招不到服务，beanName" + rpcRequest.getClassName());
        }
        //4.解析请求中的方法名称、参数类型、参数信息
        Class<?> serviceBeanClass = serviceBean.getClass();
        String methodName = rpcRequest.getMethodName();
        Class<?>[] parameterTypes = rpcRequest.getParameterTypes();
        Object[] parameters = rpcRequest.getParameters();
        //5.通过反射调用bean的方法 -通过CGLib反射调用
        FastClass fastClass = FastClass.create(serviceBeanClass);
        FastMethod method = fastClass.getMethod(methodName, parameterTypes);
        return method.invoke(serviceBean, parameters);

    }

}
